TS Saline Agar, also known as Triple Sugar Saline Iron Agar, follows the ISO 8914:1990 guidelines for identifying Vibrio parahaemolyticus. This medium capitalizes on the fermentation capabilities of organisms, particularly their ability to ferment glucose, resulting in various acid production and color changes from red to yellow. Notably, more acid is generated in the butt (fermentation) compared to the slant (respiration).
During growth, bacteria also produce alkaline byproducts through oxidative decarboxylation of peptone, which serves to neutralize the substantial acid levels in the butt. Consequently, the presence of an alkaline (red) slant and an acid (yellow) butt post-incubation signifies an organism's capacity to ferment glucose.
On the other hand, bacteria that can ferment lactose, sucrose, or both, in addition to glucose, generate copious amounts of acid, preventing pH reversion and leading to both an acid slant and acid butt.
Gas production, typically in the form of carbon dioxide (CO2), is detected by the presence of cracks or bubbles in the medium when the accumulated gas is released.
Moreover, several bacterial species reduce thiosulphate to hydrogen sulphide, which then reacts with ferric ions from ferric salts to form a distinctive insoluble black precipitate known as ferrous sulphide. This reduction process takes place in an acidic environment, commonly observed in the butt of the tube.
In summary, TS Saline Agar is a valuable tool for identifying specific bacterial characteristics, particularly in the context of glucose, lactose, sucrose fermentation, and gas production, which aid in the differentiation and classification of microbial organisms.